Container panel with antifracture score



Oct. 22, 1968 J. c. JASPER 3,406,866

CONTAINER PANEL WITH ANTI-FRACTURE SCORE med June 16, 1967 INVENT OR JOHN C.JASPER WZVMVME, My ghw T'TORNEYS 3,406,866 CONTAINER PANEL WITHANTI- FRACTURE SCORE John .C. Jasper, .Hinsdale, Ill.,.assignor to Continental Can Company, Inc., New York, N.Y., a corporation of -NeW.Yrk a a Filed June 16, 1 967, S er. No. 646,681 9Claims. (Cl. 220-54) f "ABSTRACT OF DISCLOSURE ,Thi s disclosure has to do with-the provision of an antifracture score in a removable panel portion of an easy opening container immediately adjacent the normal weakening score line. ,The anti-fracture score-'results-in the flow of ,metal towards the weakening line score and the metal relieves stress areasat the weakening line .score so as toprevent the (accidental fracture of the container panel along the weakening line score.

This invention relatesin general to new and useful improvements ineasy opening container ends, and more particularly-,tothe improvement of such container ends by the provision. of. an anti-fracture score therein.

Easy opening can ends are each provided with a score line defining a weakening line along which the can end may be ruptured tofacilita te the removal of a panel portion. The score lines are formed by a punch press operation with the result that there is not a cutting away of the metal, but a compressing of the metal. The score lines are generally trapezoidal in cross section and when formed in sheet metal, strain risers are formed at the bottom corners thereof. As a result, when any undue force or load is applied against the removable panel portion, there is a tendency for the can end to rupture along the line of one of the strain risers. This invention relates to the elimination of this undesired condition.

It has been found, in accordance with this invention, that if a further score is formed in the removable panel portion immediately adjacent the weakening score line, the strain risers normally associated with the weakening score line are greatly relieved. At the same time, the usual strain risers at the second score line are not as great as those which exist when a single score line is formed.

In accordance with the foregoing, the secondary score line formed in the removable panel portion may be considered an anti-fracture score. Rupture of the end panel along the anti-fracture score as opposed to rupture along the weakening score line does not occur because of the reduction of strain risers therealong due to its association with the weakening score line, and because the anti-fracture score is of a lesser depth than the weakening score line.

With the above and other objects in view that will hereinafter appear, the nature of the invention will be more clearly understood by reference to the following detailed description, the appended claims and the several views illustrated in the accompanying drawing:

In the drawing:

FIGURE 1 is a plan view of a conventional type of easy opening container end formed prior to this invention.

FIGURE 1A is an enlarged fragmentary transverse sectional view taken along the line 1A1A of FIGURE 1 and shows the arrangement of strain forces in the container panel at the score line.

FIGURE 2 is a plan view similar to FIGURE 1 and shows a container end provided with an anti-fracture score line in accordance with this invention.

FIGURE 3 is an enlarged fragmentary vertical sec- 3,406,866 Patented Oct. 22, 1968 tional view taken along the line 3-3 of FIGURE 2 and shows the strain pattern in the end panel in the area 01 the two score lines.

Referring now to the drawings in detail, it will be seen that there is illustrated in FIGURE 1 a conventional type of container end which is generally referred to by the numeral 5. The container end includes a peripheral seam forming portion 6 and an end panel 7. A major portion of the end panel 7 is removable in the opening of the associated container, this removal of the end panel major portion being facilitated by means of a score line 8. The removable panel portion has attached thereto by means of a rivet 9 a pull tab 10 of a conventional type. The pull tab 10 functions as a lever and results in the fracture of the end panel 7 along the score line 8 with the result that the portion of the end panel 7 defined by the score 11:lI]1j6180may be removed as a unit utilizing only the pull The score line 8 is formed in the end panel 7 by a punching operation utilizing a conventional type of scoring die (not shown). The resultant score line 8 has a generally trapezoidal cross section, as is shown in FIGURE 1A. Inasmuch as the score line 8 is formed by a punchmg or pressing operation, there is no removal of metal. On the other hand, the metal of the end panel 7 is compressed and there exists in the metal of the end panel 7 in the vicinity of the score line 8 highly concentrated internal pressures as indicated by the metal flow or strain lines 11. The concentration of stress forces results in' strain risers generally along the lines A-A and B-B of FIGURE 1A. Accordingly, when the end panel 7 is unduly stressed, accidental rupture thereof will occur at the score line 8 along one of the strain risers. This invention has to do with the elimination of the strain risers.

Referring now to FIGURE 2, it will be seen that there is illustrated a can end which constitutes an improvement over the can end 5 of FIGURE 1, the can end of FIGURE 2 being generally referred to by the numeral 15. The can end 15 includes a peripheral seam forming portion 16 and an end panel 17. The end panel 17 is provided with a score line 18 defining a removable panel portion 19. Like the can end 5, the can end 15 has formed in the removable panel portion 19 a rivet 20 which is utilized to secure in place a pull tab 21. The pull tab 21 is of the lever type and is utilized for the purpose of initiating rupture of the end panel 17 along the score line 18, followed by the tearing out of the removable panel portion 19.

The can end 15 differs from the can end 5 in that the removable panel portion 19 thereof is provided with a second score line 22. The score line 22 is an anti-fracture score line and is formed in the removable panel portion 19 immediately adjacent the score line 18. However, the anti-fracture score line 22 is shallower than the weakening score line 18, as is clearly shown in FIG- URE 3.

The score lines 18 and 22 are both formed by a punching or pressing operation during which the metal of the end panel 17 is compressed and closed generally laterally. The score forming operations result in the forming of internal compressive stresses within the end panel 17, as is generally defined by the strain lines 23. A compari son of the strain lines 23 with the strain lines 11 of FIGURE 1A will clearly show that there is a better distribution of the compressive forces within the end panel 17 in the vicinity of the score line 18 than there exists in the end panel 7 in the vicinity of the score line 8. Furthermore, it will be readily apparent that the strain risers found in the end panel 7 are greatly diminished in the end panel 17.

with a single score, it is to be noted that the stress risers with respect to the anti-fracture score 22 are also at a minimum. In view of the fact that the score 22 is shallower than the score 18, it will be readily apparent that the provision of the score 22 will not provide a line of primary fracture failure as opposed to the weakening score line 18. Tests have proved that where there is failure of the end panel 17 due to accidental fracture, it will occur along the weakening score line 18 and not along the anti-fracture score 22.

The anti-fracture score 22 has been found to be effective with respect to can ends formed from sheet metal having a thickness ranging from 0.008 inch to 0.014 inch. It also has been found that there is a limit as to the center-to-center spacing of the scores 18 and 22. When the scores are brought too close together, the end panel is too greatly weakened in the narrow areaand when the scores are too far apart, the forming of the anti-fracture score has no influence on the weakening score line. The practical range of the center-to-center spacing between the score line 18 and the anti-fracture score 22 is from 0.050 inch to 0.125 inch with the optimum spacing being on the order of 0.080 inch. Also, it has been found that there is a most effective differential in score depths irrespective of the score depths. This differential is on the order of 0.003 inch with the antifracture score 22 being shallower than the weakening ,said. panel and normally resultingjn stressed .areasalong the bottom corners of saidscore, the improvement comprising an anti-fracture score formed in said removable panel portion adjacent said score line, and said score line being relieved of the normal stressed areas by the position of the anti-fracture score adjacent the first-men tioned score line.

-2. The container panel of claim 1 wherein said antifracture score is shallower than saidscore line.

3. The container panel of claim 1 wherein said antifracture score is shallower than said score line by a dimension on the order of 0.003 inch.

4. The container panel of-claim 1 wherein the centerto-center spacing of said score line and said anti-fracture score is on the order of 0.080 inch.

5. The container panel of claim 1 wherein the centerto-center' spacing of said score line and said anti-fracture score ranges from 0.050 inch to 0.125 inch.

6. The container panel of claim 1 wherein said score line and said anti-fracture score are circular in outline and disposed in concentric relation.

'7. The container panel of claim 1 wherein said antifracture score is uniformly spaced from said score line.

8. The container panel of claim 1 wherein said panel is an end panel of a container end.

9. The container panel of claim 1 wherein said antifracture score is shallower than said score line, and the center-to-center spacing of said score line and said antifracture score is on the order of 0.080 inch.

References Cited UNITED STATES PATENTS 3,322,296 5/1967 Khoury 220-S4 3,338,199 8/1967 Taylor 11315 THERON E. CONDON, Primary Examiner.

G. T. HALL, Assistant Examiner.

Disclaimer and Dedication 3,406,866.Jolm U. Jasper, Hinsdale, Ill. CONTAINER PANEL WITH ANTI-FRACTURE SCORE. Patent dated Oct. 22, 1968. Disclaimer filed May 22, 1969, by the assignee, Uontinental Gan Hereby dlsclaims and dedicates to the Public the entire term of said patent.

[Oficial Gazette July J5, 1.969.] 

